Against my better judgement I made an aluminium disc for a 100cc sprint kart about 20 years ago. Was made from the garden variety 5083 H321 plate and electroless nickel plated. It held up for at least a couple of meetings despite my dire predictions and I had no report of it's failure.

Aluminium has about twice the heat capacity of iron, or stainless steel, so for a given energy input an Al. disc half the weight would absorb the same amount. They must have been running pretty cool though.

Forum is my preferred info gathering area . I too found the bitching got on my nerves a while back and dropped out for quite a time , glad it seems to have died away . I find the knowledge on here is broader with less of the "what bike have I got bro's "type of questions or how can I get my 1977 xyz to go quick what sort of power band should I get ?Iain .

Yep. It is an archived resource that people from all over the world access. Face book is useless for all practical purposes after a month or two, and that's on the off chance something was discussed in depth.